Modern mattresses typically include an inner construction, such as a spring assembly, covered by a mattress sack. A mattress sack typically includes a top panel and a bottom panel which are joined together by a side panel extending around the perimeter of the mattress sack. A box spring enclosure also includes a top and bottom panel joined by a side panel.
In one technique used to form a mattress sack, or a box spring enclosure; top and bottom panels are first cut to size and hemmed. Typically, the top and bottom panels are quilted and include a layer of foam or other insulating material between two fabric layers. Thereafter, an elongated strip of material, which could be the same material used to form the top or bottom panels, is cut to a suitable length and width to be used as a side panel. The ends of this elongated strip of material are sewn together at a predetermined point, and this endless band is then turned inside out so that the stitch is positioned on the inside facing the inner construction of the mattress or box spring. One lateral edge of this endless band is then stitched to a top or bottom panel along with flange material in a tape edge operation, in which a folded piece of tape material is wrapped about the joined edges of the side and top or bottom panel and flange material, and the entire composite structure is sewn together. The inner construction of the mattress or box spring is then placed within this partially formed mattress sack or box spring enclosure, and the remaining top or bottom panel is then stitched to the opposite lateral edge of the side panel, using a tape edge operation, to completely enclose the inner construction. At this point, the mattress or box spring is substantially finished.
Presently, when the side panel is formed, a strip of material to be used as the side panel is folded in half along a transverse fold so that the two ends are facing in the same direction, are aligned and are placed next to one another along one surface of the strip of material. These two ends are then passed through a conventional single needle chain stitch sewing machine manually to stitch the ends together at a point spaced from the ends of the panel toward the fold in the center of the panel, and along a line transverse to the direction of elongation of the strip. This sewing step typically is repeated at another location spaced from the first stitch to provide strength to the stitch. Presently, this step is not automated. The operator is required to adjust the position of the ends of the side panel manually and manually align them to stitch the ends together at the proper point. As can be imagined, the present method produces a certain amount of error. Sometimes, the stitch is placed too close to the ends of the panel, and the side panel has too large a circumference. Sometimes, the stitch is spaced too far away from the ends of the panel and the circumference of the side panel is too small for the mattress for which it is designed. Either result produces some difficulty in the step of attaching the side panel to the top and bottom panels and a certain amount of manual, time-consuming manipulation of the fabric is required to produce a usable final product. Moreover, passing the side panel twice through the sewing machine and manually adjusting the position of the side panel both take extra time, thus increasing labor costs and reducing safety for the operator.
One object of the present invention is to automate the step of sewing together the ends of the side panel.
Another object of the present invention is to provide a sewing machine which is particularly suited for sewing together the ends of a side panel of a mattress sack with precision while providing a high level of safety for the operator.